The massive strength of a wide 6-screw ring is combined with lightweight yet thick cross section aluminum to provide a reliable return-to-zero ultra strong mounting system for Picatinny-style rails. Available in four heights from 1/4" to 1", Burris Xtreme Military 30mm Picatinni Rail Weapon Rings are ready for the heaviest of scopes, massive recoil, and severe usage.Mail Order Catalog - Internet Only